Finally, Pinterest knows what it wants to be. Now how about that API?

By now, Pinterest should be well aware of how hungry startups are for its API.

As one of the four social horsemen bursting on the scene in late 2011 from seemingly nowhere, the company has been very careful not to mess things up by releasing its API too early. That was understandable. One of the other social horsemen-- Twitter-- released its API pretty much immediately and suffered Fail Whales and huge fragmentation as a result. It was only years -- and a lot of developer angst later-- that all that chaos was rectified.

But while caution might be prudent, Pinterest is pushing it. We've been anticipating this thing since, well, late 2011. The eager conversions with developers hopeful to build apps and tools for the platform were loud at first. Lately it seems like they've faded. Hopeful startups are dropping the word "pin" from their names in droves. It feels like people are starting to lose interest.

Then this month, the hiring of John Yi to lead Pinterest's "Marketing Developer Partnerships" has reignited speculation that an API is finally coming. Yi worked on API integration at Facebook-- another social horseman and a master of deliberate pacing compared to Twitter.

Another reason that the API may be at long last approaching? Pinterest finally seems to know what it is. It's not a wish fulfillment ecommerce generator, as many had speculated. It is yet anther big eyeball ad business.

I always attributed the slow pace to the fact that Pinterest didn't know what it wanted to be when it grew up. The company hit millions of users in a year. Similar to what Twitter and Tumblr experienced in their early days of fast-accelerating growth, Pinterest likely spent many of its early resources keeping the site running and managing the traffic.

The problem with being an overnight success (even if it was several years in the making) is that suddenly the time for experimenting is over. Now you have something so precious that you want to do everything you can to not screw it up.

Initially, everyone thought Pinterest would be a shoo-in to monetize with commerce. After all, Pinterest is a place where people self-define by what they want to own, rather than what they had for lunch or who they are friends with. Look at those conversions! Ladies on Pinterest be shopping! Or something. All Pinterest needed was a "buy" button.

So what happened on the way to becoming a commerce powerhouse? The overhyped social commerce category fizzled out amid several disappointing failures.

Turns out the commerce business is less attractive than one might think. Affiliate linking to Amazon isn't the most glamorous or innovative business for a hot Silicon Valley startup valued at $2.5 billion. And Pinterest's pins are littered with un-shoppable stuff. Separating those out would be impossible and probably piss off users. At the D11 conference this year, Silberman hinted he was wary that commerce on Pinterest could "commodify someone's passions," which would hurt the site in the long run.

Beyond that, studies show Facebook -- not Pinterest -- still drives the most conversions and highest basket sizes from social media. And even Facebook has been unable to make social commerce work through several attempts. F-commerce was a bust. Gifts started out rocky and hasn't become a significant part of earnings. Prior to that, Beacon was killed off also.

There are a litany of failed startups that sought to replicate shopping with your friends online. It sounds good, but so far social commerce just hasn't caught on in practice.

That isn't stopping others, though. Companies that watched Pinterest's initial explosion have sprung up with similar commerce-focused offerings. Wanelo, for example, offers a feed of 100 percent shoppable items. But the site doesn't process transactions itself yet. It may be in the works but it is a tricky problem to solve because it requires working directly with thousands of vendors. The best way to tie commerce and social media together, it seems, is to start with a commerce site and "Pinterestify" it, as sites like Fab and Open Sky have with their own browsable feeds.

Years later (a lifetime for startups), and with commerce out the window, Pinterest is left with an obvious identity: an advertising company. Of some sort. "(CEO) Ben (Silverman) said earlier this year that we will explore advertising as a business model at some point but we're not there yet," Pinterest spokesperson Barry Schnitt wrote in an email last month. Silberman alluded to this at the Conversational Market Summit during Internet Week, when the company rolled out new analytics for brands using the service.

To varying degrees, Facebook and Twitter have fostered ecosystems of partners who build tools on their APIs. The idea is to give advertisers a rich array of options and tools to buy when they decide to spend money advertising on Pinterest.

Adtech startups have been salivating over the possibilities since Pinterest took off in 2011. Even with no API available to build on, many startups hacked together some version of a tool that scrapes data to mimic real ad analytics.

These startups did so in the hopes that they wouldn't be stuck with those hacked together data scraping tools for long. The minute Pinterest opened up an API, they'd be the dominant players on a new platform. It looked like the early days of Facebook marketing. Buddy Media started out knowing it wanted to do some sort of advertising on Facebook; it didn't have its "aha" moment until Facebook unveiled Pages in 2007. Four years later the company sold to Salesforce for $689 million.

Pinterest hasn't moved as quickly as these eager startups. While waiting for the API on which to build more robust advertising tools, half of them have sold, given up or at the very least gotten rid of the word "pin" in their names, likely because brands have diminished interest in lookalike scraping tools for Pinterest. Pinerly is now Reachli. Pingage changed its name to Ahalogy. Curalate added Instagram. Pinpuff sold itself to Science Inc. and is now part of HelloSociety. PinReach put itself for sale on what amounts to an eBay for abandoned startups. Update: A Pinterest rep reached out to say that Pinerly and and Pingage changed their names because Pinterest does not allow other companies to use the word "pin" in their names. "We requested these companies update their names, and they complied," the press representative wrote.

At this point, all those startups aiming to capitalize on Pinterest are still not even a "partner" to the company, they're just long time hangers-on. It's like Fred Wilson famously said: "Dont be a Google bitch, don't be a Facebook bitch, don't be a Twitter bitch." If asked to revise the statement today, I'm sure he'd happily add, "Don't be a Pinterest bitch."